The present invention relates to signal peak sensing and more particularly to a versatile, low-cost digital sensor capable of accurately detecting the occurrence of peaks in analog signals. Although the circuits described herein are specifically concerned with sensing the peaks of analog magnetic field signals, peak sensing in other types of analog signals may also be performed in accordance with the principles of the present invention.
Magnetically influenced mine fuzes operate on the magnetic field intensity signal associated with target vehicles such as tanks. The goal is to detect when the field signal has peaked so that the fuze can be fired at the proper time relative to the position of the vehicle. Prior art attempts at providing such fuzes include a magnetic dip needle threshold detector. This approach suffers from a tendency toward firing too early in response to high amplitude magnetic signatures of vehicles travelling at low speeds and firing too late in response to small amplitude signatures of high speed vehicles. The problem derives from the fact that absolute threshold level detection does not account for either variations in the different magnetic signature amplitudes presented by different vehicles or vehicle speed. It was therefore subsequently determined that a more accurate firing time is achieved if the magnetic field amplitude is sensed to first determine if a threshold has been reached and to then determine when the amplitude begins to change in an opposite sense (i.e.--begins to decrease from a peak). Detecting the threshold first minimizes the possibility that noise will trigger the fuze. Subsequent detection of an over-the-peak condition assures that the vehicle is still over the mine. In spite of this recognition of a better criterion for fuze firing, prior art fuzes employing this criterion have the disadvantages of lack of versatility, high cost, and large size. These disadvantages derive because prior art fuzes have processed the magnetic field signal in analog form.
It is therefore an object of the present invention to provide a low-cost, versatile digital mine fuze.
It is another object of the present invention to provide a low-cost, versatile digital mine fuze which provides a firing signal after detecting an analog threshold level followed by an over-the-peak signal condition.
In a more general sense, it is an object of the present invention to provide a digital approach to sensing analog signal peaks, or more accurately, for sensing the beginning of a fall off from such signal peaks.